Multi-well filtration apparatus are well known in the art, and are used for the assay of biological liquids. Examples of such apparatus are disclosed in U.S. Pat. Nos. 5,035,861, 4,948,442, 4,902,481, 4,828,386, 4,777,021, 4,734,192, 4,704,255, 4,642,220, 4,526,690, 4,427,415, 4,246,339, and 4,154,795, and in U.S. patent application Ser. No. 07/671,448, filed Mar. 19, 1991.
Known multi-well filtration apparatus typically comprise a multi-well filtration plate and a housing. A conventional multi-well filtration plate has 96 wells for performing multiple assays simultaneously. Each well typically contains a filter for separating a biological component from the liquid that is introduced into the apparatus. Typically, the housing will receive the filtrate that passes through the filter in each well. A vacuum chamber is usually provided in the housing for drawing the liquid through each filter.
Frequently, there are occasions when a multitude of samples need to be tested in a multi-well filtration apparatus. When these occasions arise, it becomes necessary to use a number of multi-well filtration plates, which have to be secured to and removed from the housing of the apparatus.
In previously-developed multi-well filtration apparatus, the multi-well filtration plate has been secured to the housing in a manner that does not promote quick and convenient removal of the multi-well filtration plate.
For example, in U.S. Pat. No. 4,427,415 a multi-well filtration plate is secured to a housing by a pair of retaining brackets and retaining bolts. The multi-well filtration plate is held beneath a projecting flange of the retaining bracket. The retaining bolts pass through the brackets into the housing and are tightened to secure the multi-well filtration plate to the housing. To remove the multi-well filtration plate, the bolts need to be loosened to disengage the brackets from the multi-well filtration plate. The multi-well filtration plate can then be removed from beneath the brackets. When a number of samples need to be tested, this becomes a relatively inefficient and time-consuming task for the user of this multi-well filtration apparatus.
In U.S. patent application Ser. No. 07/671,448, the multi-well filtration plate is attached to the housing by placing a bracket over the plate and closing two latches that are attached to the bracket. To remove the multi-well filtration plate from the housing of the apparatus of U.S. application Ser. No. 07/671,448, each latch must be opened, and the bracket must be removed from the housing. This is a time-consuming task and is a hassle to the user of the apparatus, particularly when many samples are being tested.